Method and apparatus for heating glass melting furnaces with fossil fuels

Abstract

During the heating of glass melting furnaces having a combustion chamber with regenerators for preheating oxidation gases, with port necks that open into the combustion chamber, with primary burners and with secondary burners that are installed in a cascade arrangement relative to the primary burners, the secondary burners are operated as cascade burners with a relatively low proportion of the fuel, the secondary fuel. Flames are thereby created in over- and sub-stoichiometric conditions and the flame gases formed are mixed with one another so that the complete combustion process in the combustion chamber is more or less stoichiometric. The secondary fuel is supplied by the secondary burners to a step, installed in the port neck. In order to prevent or reduce soot and graphite deposits in the step without increasing the nitrogen oxide content in the furnace waste gases, a secondary oxidation gas is blown into step during the firing phase of each port neck in addition to the primary oxidation gas preheated in the regenerators that flows over the step. If significant deposits of carbon material and/or temperature problems occur, then in a similar way an oxidation gas can be blown in during the exhaust phase for the furnace waste gases of each port neck when the secondary burner is switched off.

1. A method for heating glass melting furnaces having a combustion chamber, with regenerators for heating primary oxidation gases from the group consisting of air, oxygen-enriched air and oxygen, and port necks which open into said combustion chamber, primary burners, and secondary burners that are installed in a cascade arrangement relative to said primary burners, whereby said primary and secondary burners are operated with fossil fuels, comprising the steps of:
 operating said primary burners with a larger proportion of said fuel as a primary fuel to produce flame gases under sub-stoichiometric conditions,  
 operating said secondary burners as cascade burners with a relatively low proportion of said fuel as secondary fuel to produce flame gases under over-stoichiometric conditions,  
 mixing together said flame gases produced so that a complete combustion process in said combustion chamber is approximately stoichiometric,  
 supplying said secondary fuel through said secondary burners through one side wall of each port neck to a step, provided in said port neck, said step having a bottom surface and a wall face,  
 introducing said preheated primary oxidation gases to flow from said regenerators over said step into said combustion chamber,  
 blowing a secondary oxidation gas from the group consisting of air, oxygen-enriched air and oxygen into said step during a firing phase of each port neck, in addition to primary oxidation gas preheated in said regenerators that flow over said step.  
 
   
   
     2. A method according to  claim 1 , wherein in a waste gas exhaust phase of each port neck an oxidation gas from the group consisting of air, oxygen-enriched air and oxygen is also blown into said step when said secondary burner is switched off. 
   
   
     3. A method according to  claim 1 , wherein said secondary oxidation gas is blown into said step in a center of said secondary burner. 
   
   
     4. A method according to  claim 1 , wherein said secondary oxidation gas is blown into said step through said side wall outside said secondary burner. 
   
   
     5. A method according to  claim 1 , wherein said secondary oxidation gas is blown into said step through said bottom surface. 
   
   
     6. A method according to  claim 1 , wherein said secondary oxidation gas is blown into said step directly in front of said wall face. 
   
   
     7. A method according to  claim 1 , wherein said secondary oxidation gas is blown into said step through said wall face. 
   
   
     8. A method according to  claim 7 , wherein said secondary oxidation gas is also blown into the step through said bottom surface. 
   
   
     9. A method according to  claim 1 , wherein fuel is mixed with said secondary oxidation gas. 
   
   
     10. A method according to  claim 1 , wherein when gaseous fuels are used, a ratio of a quantity of said secondary fuel to said primary fuel quantity is chosen between 5 and 30 volume percent. 
   
   
     11. A method according to  claim 10 , wherein said ratio is between 10 and 20 volume percent. 
   
   
     12. A method according to  claim 1 , wherein in the firing phase an amount of oxygen in said secondary oxidation gas blown into said step and an amount of oxygen in said primary oxidation gases, preheated in said regenerators, supplied through said port neck are at a ratio within a range 0.5 to 2.5. 
   
   
     13. A method according to  claim 1 , wherein an amount of secondary oxidation gas blown into said step during said firing phase and an amount of secondary oxidation gas blown into said step during an exhaust phase are at a ratio within a range 0.5 to 1.5. 
   
   
     14. A method according to  claim 13 , wherein said ratio is between 0.8 and 1.2. 
   
   
     15. A method according to  claim 1 , wherein a quantity ratio of said secondary oxidation gas is adjusted by variable fans.